Implement 'load' on Model and ItemManager

[zanerock]

Pull request to resolve #28

Submitted by: zanerock

Instructions

Review all code changes. Verify the submitter attestations belowe, checking off each statement to indicate that you have reviewed the statement and it is true to the best of your knowledge. If you do not agree with or are unsure of a statement, then add a comment describing your questions or concerns and contact the submitter @zanerock for clarification.

QA files

• Lint record
• Unit test record

Submitter attestations

To be verified by reviewer.

• Do the changes implement all concrete TODOs in the change ticket? y (CHANGES_IMPLEMENT_ALL_TODOS=true)
• Are there other changes not described in the original work description? n (CHANGES_HAS_ADDITIONAL_CHANGES=false)
• Are there any QA exceptions which need to be addressed? n (CHANGES_HAS_QA_EXCEPTIONS=false)
• Do the changes add or involve connections, authentication, or queries to a database or any third-party service? n (CHANGES_THIRD_PARTY_SERVICES_MODIFIED=false)
• Has all debug, hard coded test data, and hard coded authentication data been removed? y (CHANGES_DEBUG_REMOVED=true)
• I have reviewed and verified the above are true to the best of my knowledge.